The present invention relates to an ocular lens material. More particularly, the present invention relates to an ocular lens material having high oxygen permeability and excellent mechanical strength, and in addition, excellent surface wettability and low frictional surface property at the same time, which can be suitably used for a contact lens, an intraocular lens, an artificial cornea and the like.
Conventionally, a soft material has been a suitable material for a contact lens which can be worn comfortably and an intraocular lens which can be transformed and inserted only by small incision of the eyeball without damaging ocular tissue.
As the above soft material, there are a water-containing material which absorbs water, swells and softens, and a material which does not contain water substantially. Oxygen permeability of the water-containing material depends on water content and does not exceed larger than oxygen permeability of water.
Examples of materials from which a water-containing contact lens with high oxygen permeability can be produced is silicone-containing hydrogel, hereinafter referred to as silicone hydrogel, which is disclosed in Japanese Unexamined Patent Publication No. 179422/1991, Japanese Unexamined Patent Publication No. 196177/1991 and Japanese Unexamined Patent Publication No. 196118/1991. The silicone hydrogel is excellent in oxygen permeability because it has higher oxygen permeability than water.
The above silicone hydrogel contains a hydrophobic component, and therefore wettability of the material surface is inferior, resulting in high sticking property of the surface when the material is molded. Furthermore, when the amount of the silicon-containing monomer is increased to improve oxygen permeability of the material, the obtained material is semi-hard, and thus it is difficult to prepare from the material a contact lens which can be comfortably worn or an intraocular lens which can be inserted only by small incision. It is certain that subjective lens comfort becomes bad when such ocular lens is worn or put in. In addition, there is a defect that deposits such as lipid is increased because of high hydrophobic property. On the other hand, when a hydrophilic component is used in a large amount to improve feeling for wearing of the material, oxygen permeability of the material must depend on water content as a matter of course.
A hydrogel material most suitable for an ocular lens has high wettability and low frictional property in addition to high oxygen permeability and ideal rigidity. Such material is most appropriate because lubricity of a lens is maintained from high wettability and low frictional property, achieving comfortable wearing of the lens on the eye. To improve wettability and lower frictional property of a material, the following methods are suggested.
For instance, U.S. Pat. No. 4,099,859 specification discloses a method of covering surface of a contact lens with a hydrophilic monomer and irradiating the surface with ultraviolet ray to graft-polymerize the hydrophilic monomer on the surface of the contact lens material made of silicone rubber. In addition, U.S. Pat. No. 4,143,949 specification discloses a method of hydrophilic coating on a hydrophobic contact lens by radiation-induced polymerization, while each of U.S. Pat. No. 4,311,573 specification and U.S. Pat. No. 4,589,964 specification discloses a method of imparting hydrophilic property to surface of a hydrophobic polymer by graft-polymerizing a vinyl monomer according to decomposition of generated peroxyl group after ozone treatment. There is another disclosure in Japanese Patent Publication No. 2898664 that a crosslinked siloxane-urethane polymer in the state of an interpenetrating network polymer, generally referred to as IPN, with a hydrophilic vinyl polymer is obtained.
However, all of the above methods have various problems such that the method involves complicated steps, uniform treatment of all lenses and confirmation of the degree of treatment are difficult, and that preparation of raw materials is difficult. A desired hydrogel material most suitable for an ocular lens cannot be easily obtained according to these methods.
In addition to the above, the following various materials are proposed.
For instance, a water-insoluble hydrophilic gel comprising a crosslinked copolymer containing 20 to 90% by weight of water-soluble monomers and water-insoluble monomers such as methyl methacrylate and 10 to 80% by weight of a hydrophobic siloxane macromer is disclosed in Japanese Unexamined Patent Publication No. 22487/1979. A hydrophilic composition having improved flexibility and oxygen permeability after hydration, which is a copolymer of a comonomer comprising 15 to 65% by weight of an amide group-containing monomer, 10 to 75% by weight of an organic silicon compound and 0.1 to 65% by weight of an ester of an alkanol and a (meth)acrylic acid is disclosed in Japanese Unexamined Patent Publication No. 500418/1980. A polysiloxane contact lens obtained by polymerizing, with other monomers, a macromer prepared by mixing an organic siloxane oligomer (I) with a (meth)acrylate monomer (II) in a molar ratio (II)/(I) of 2.0 to 2.6 and reacting the mixture with diisocyanate is disclosed in Japanese Unexamined Patent Publication No. 46311/1992. An ocular lens material comprising a copolymer containing a polysiloxane macromonomer and an alkyl(meth)acrylamide as main components in a weight ratio, the polysiloxane macromonomer/the alkyl(meth)acrylamide, of 5/95 to 90/10 is disclosed in Japanese Unexamined Patent Publication No. 121826/1994.
Being obtained from a component containing silicon, particularly silicone, all of the above gel, composition, contact lens and material have excellent oxygen permeability. However, surface wettability is not particularly good or friction property is not sufficiently low, which means that oxygen permeability, surface wettability and low friction property are not achieved simultaneously.
The present invention has been carried in view of the above prior arts. The object of the present invention is to provide an ocular lens material having excellent surface wettability and low surface frictional property in addition to high oxygen permeability and high mechanical strength.
The present invention relates to an ocular lens material comprising a copolymer prepared by polymerization with heating a monomer mixture and/or with irradiating a monomer mixture with ultraviolet ray by means of a molding method, said monomer mixture containing, as main components,
(A) a polysiloxane macromonomer in which a polymerizable group bonds to a siloxane main chain through at least one urethane bond, and which is represented by the formula (I):
A1-U1-(xe2x80x94S1xe2x80x94U2xe2x80x94)nxe2x80x94S2xe2x80x94U3xe2x80x94A2xe2x80x83xe2x80x83(I)
wherein A1 is a group represented by the formula (II):
Y21xe2x80x94Z21xe2x80x94R31xe2x80x83xe2x80x83(II)
in which Y21 is acryloyl group, vinyl group or allyl group, Z21 is oxygen atom or direct bond, and R31 is direct bond or a linear, branched or aromatic alkylene group having 1 to 12 carbon atoms; A2 is a group represented by the formula (III):
xe2x80x94R34xe2x80x94Z22xe2x80x94Y22xe2x80x83xe2x80x83(III)
in which Y22 is acryloyl group, vinyl group or allyl group, Z22 is oxygen atom or direct bond, and R34 is direct bond or a linear, branched or aromatic alkylene group having 1 to 12 carbon atoms, where Y21 in the formula (II) and Y22 in the formula (III) may be the same or different;
U1 is a group represented by the formula (IV):
xe2x80x94X21-E21xe2x80x94X25xe2x80x94R32xe2x80x94xe2x80x83xe2x80x83(IV)
in which each of X21 and X25 is independently selected from direct bond, oxygen atom and an alkylene glycol group, E21 is xe2x80x94NHCOxe2x80x94 group (in this case, X21 is direct bond, X25 is oxygen atom or an alkylene glycol group and E21 and X25 form urethane bond), xe2x80x94CONHxe2x80x94 group (in this case, X21 is oxygen atom or an alkylene glycol group, X25 is direct bond and E21 and X21 form urethane bond) or a divalent group derived from a diisocyanate selected from a group of a saturated or unsaturated aliphatic diisocyanate, an alicyclic diisocyanate and an aromatic diisocyanate (in this case, each of X21 and X25 is independently selected from oxygen atom and an alkylene glycol group and E21 and X21, E21 and X25 form two urethane bonds, respectively) and R32 is a linear or branched alkylene group having 1 to 6 carbon atoms; each of S1 and S2 is independently a group represented by the formula (V): 
in which each of R23, R24, R25, R26, R27 and R28 is independently an alkyl group having 1 to 6 carbon atoms, an alkyl group substituted with fluorine atom or phenyl group, K is an integer of 1 to 1,500, L is 0 or an integer of 1 to 1,499, and K+L is an integer of 1 to 1,500; U2 is a group represented by the formula (VI):
xe2x80x83xe2x80x94R37xe2x80x94X27-E24xe2x80x94X28xe2x80x94R38xe2x80x94xe2x80x83xe2x80x83(VI)
in which each of R37 and R38 is independently a linear or branched alkylene group having 1 to 6 carbon atoms, each of X27 and X28 is independently oxygen atom or an alkylene glycol group, and E24 is a divalent group derived from a diisocyanate selected from a group of a saturated or unsaturated aliphatic diisocyanate, an alicyclic diisocyanate and an aromatic diisocyanate (in this case, E24 and X27, E24 and X28 form two urethane bonds, respectively); U3 is a group represented by the formula (VII):
xe2x80x94R33xe2x80x94X26-E22xe2x80x94X22xe2x80x94xe2x80x83xe2x80x83(VII)
in which R33 is a linear or branched alkylene group having 1 to 6 carbon atoms, each of X22 and X26 is independently selected from direct bond, oxygen atom and an alkylene glycol group, E22 is xe2x80x94NHCOxe2x80x94 group (in this case, X22 is oxygen atom or an alkylene glycol group, X26 is direct bond and E22 and X22 form urethane bond), xe2x80x94CONHxe2x80x94 group (in this case, X22 is direct bond, X26 is oxygen atom or an alkylene glycol group and E22 and X26 form urethane bond) or a divalent group derived from a diisocyanate selected from a group of a saturated or unsaturated aliphatic diisocyanate, an alicyclic diisocyanate and an aromatic diisocyanate (in this case, each of X22 and X26 is independently oxygen atom or an alkylene glycol group and E22 and X22, E22 and X26 form two urethane bonds, respectively); and
n is 0 or an integer of 1 to 10,
(B) a silicon-containing alkyl methacrylate,
(C) a hydrophilic monomer comprising
(C-1) N-vinylpyrrolidone and
(C-2) a hydrophilic monomer excepting N-vinylpyrrolidone (C-1), containing acryloyl group, vinyl group or allyl group;
(D) at least one monomer selected from an alkyl (meth)acrylate and a fluorine-containing alkyl (meth)acrylate; and
(E) a low molecular weight crosslinkable monomer comprising
(E-1) a crosslinkable monomer containing at least one group selected from acryloyl group, vinyl group and allyl group, and another group of methacryloyl group, and
(E-2) a crosslinkable monomer containing at least two methacryloyl groups,
wherein the weight ratio of the total of the polysiloxane macromonomer (A) and the silicon-containing alkyl methacrylate (B) to the hydrophilic monomer (C), the total weight of (A) and (B)/the weight of (C), is 30/70 to 70/30,
the weight ratio of the polysiloxane macromonomer (A) to the silicon-containing alkyl methacrylate (B), the weight of (A)/the weight of (B), is 25/75 to 75/25,
the weight ratio of N-vinylpyrrolidone (C-1) to the hydrophilic monomer (C-2), the weight of (C-1)/the weight of (C-2), is 50/50 to 100/0, and the amount of the monomer (D) in the monomer mixture is 0 to 20% by weight.